Screw-retaining device.



E. E. GREAVES.

SCREW RETAINING DEVICE.

LIGATION I'lL AP 1 .1 1914. 1,105,647; Patented Aug. 4, 1914,

UNITED STATES "PATENT OFFICE.

EDWIN E. GREAVES, OF SYRACUSE, NEW YORK, ASSIGNOR TO CROUSE-HINDS COMPANY, OF SYRACUSE, NEW YORK, A CORPORATION OF NEW YORK.

SCREW-RETAINING DEVICE.

Specification of Letters Patent.

Patented Aug. 4., 1914.

Application filed March 10, 1914. Serial No. 823,685.

To all whom it may concern:

Be it known that I, EDWIN E. GRnAvns, a citizen of the United States, and a resldent of Syracuse, in the county of ()nondaga and State of New York, have invented a oertam new and useful Screw-Retaining )ev1c'e, of which the followingis aspeclfication.

This invention has for its object a screw retaining device particularly appllcable for preventing the screws, WhlCh secure the covers to electrical conduit outlet boxes, from removal from the covers; and it c0ns1sts 1n the novel features of construction hereinafter set forth and claimed.

In describing this invention, reference 1s had to the accompanying drawings, in wh1ch like characters'designate corresponding parts in all the views.

Figure 1 is a sectional view, partly in elevation, of one form of conduit outlet box, the screws of which are provided with my invention. Fig. 2 is an inverted plan view of the cover. Fig. 3 is a plan view of the screw retaining device. Fig. 4 is a crosssectional view thereof. Figs. 5, 6 and 7 are enlarged fragmentary sectional views through the cover, Fig. 5 illustratlng the screw retaining device .when placed on the screw, Fig. 6 showing said device when moved into operative position, and Fig. 7 illustrating the action of the device when an attempt is made to pull the screw out of the hole. Fig. 8 is a view, partly in section, showing the dies and punches and the operations used informing this screw retaining device.

Thisscrew retaining device comprises a washer which is here shown in the form of a disk, the washer having a marginal portion and a hollow, axially-projected, truncated, conoidal boss and a perforation at the top of the boss of less diameter thanthe screw with which the device is designed to be used, the edge of the boss around the perforation being compressed so that it is of greater densitv and hardness than the remaining part of the boss and is rigid compared with the remaining part of the boss,

.. which part is comparatively flexible so that the boss can flatten toward the plane of the body' of the washer. The compressed or condensed edge around the perforation of the boss is so thin that a ortion thereof will take into the threads 0 the screw. I 1 designates a conduit outlet box, and 2 the cover therefor, which is retained in position by screws 3 usuallypassing through unthreaded openings 4; in the cover and threading into lugs 5 in the box. The openings 4 are of larger diameter that the screws 3 and extend through the cover, and preferably corresponding ends of the openings 4 communicate with recesses or countersinks inclosed by ribs projecting from one face of the cover concentric to said openings and spaced apart therefrom. The heads of the screws engage the opposite face of the cover about the other ends of the openings 4.

6 designates the screw retaining device in the form of a disk ofless, diameter than the ribs inclosing the recesses or countersinks communicating with corresponding ends of the openings 4:, said device having an axially-projected, truncated, conoidal boss 7 which has a perforation at the top thereof of less diameter than the threaded part of the screw 3.

The walls of the boss 7 taper toward the perforation, as seen in Fig. 4, forming a thin edge around the perforation so that said edge 8 or a portion thereof will take into the threadsof the screw, as seen in Figs. 6 and 7. The thinning of the edge 8 around the perforation is formed by compressing said edge, which edge before being compressed is of the same thickness as the major part of the boss and washer, as seen in Fig. 8. As here shown, the upper side of the boss is formed slightly convex,'and the lower side is conical, the convex surface curving at 9 into a plane approximately parallel to the body of the washer as the curved surface nears the edge 8. The curving of the upper face of the boss arranges the thin edge 8 in position to engage the threads most effectively, and the arrangement of the conical inner surface braces said edge and tends to prevent the tearing away of the same.

This screw retaining device is formed by dies, as seen in Fig. 8, and the blank 10 is placed in the female lower die 11 and the upper die 12 which also carries a punch 13, first punches erforation in the blank 10 and then the ma e die 12. cooperatin with the lower die 11 forms the boss 7 an com,- presses the margin thereof around the'perforation with the edge 8.

In operation, this screw retaining device is first placed on the end of the screw as he as and for the purpose specified,

indicated in Fig. and forced along the screwinto the position shown in Fig. 6, in which it is located at the bottom of a countersink at the inner end of the unthreaded 5 screw hole 4:. As the perforation is of smaller diameter than the screw, the thin margin 8 around the perforation has a sort of ratcheting action over the thread due to the slight flexibility of the major part of the boss, and when the screw is pulled outwardly a portion or portions of the hard thin edge around the perforation take into the threads if a force is applied to the screw tending to flatten the cone toward a plane, as seen in Fig. 7-.

What I claim is:

1. A deviceforrretaining a screw in an opening larger in diameter than the shank of the screw, said opening extending entirely through a body, and the head of the screw engaging with/one face of the body about one end of the'opening, said device engaging with the portion of the screw shank projecting beyond the opposite face of the body and coacting'with said face lastnamed, T and comprising a disk having a marginal portion and a central portion odset from the marginal portion in the direction of {the end of the screw shank, and provided 1 with a central opening tapering inwardly fromthe face of the disk opposite to that from which the central portion is ofiset, the portion of said tapering opening of smaller diameter being of less diameter than the screw thread on the shank, and

' said device being flexible and slidable lengthwise of the shank from the end thereof toward the head of the screw, substantially as and for the purpose described.

2. 'A device for retaining a screw in an opening larger in diameter than the shank of the screw, said opening extending through a body, and the head of the screw cooperating with one face of the body, said device as engaging with the portion of the screw shankprojecting beyond the opposite face of the body, and comprising a disk having a marginal portion and an ofl'set portion having a'tapering wall, said disk having a to central opening through the-same, a portion of, the wall of the part of said opening passing through the offset" portion of the disk being of less thickness. than the major portion of the disk and of less diameter than ,5- the screw shank, said ofiset portion ielding for permitting the disk to be orced lengthwise of the shank from the end thereof toward the head of the screw an'd'closing in to grip the threads of the shank when the disk contacts with the adjacent face of the body and the screw is movedfltoward the front facethereof, causing a relative movement toward the disk of the end of the shank opposite the head of the screw, substantially paratively flexible and capable of flattening mo em 3. A combined cover and securing means therefor, comprising a plate having an opena ing extending entirely through the same transversely thereof, a screw having a threaded shank passing loosely through said opening and a head for coiiperating with one face of the plate for preventing relative movement of the screw in one direction, and a disk of a diameter greater than said opening slidable lengthwise of the shank of the 5 screw in one direction and frictionally engaging the same, said disk being carried by the part of the shank projecting beyond the face of the plate opposite to that with which the head of the screw coacts, and cotiperatg0 ing with said face for limiting the movement of the screw in a second direction, substantially as and for the purpose set forth.

4;. A combined cover and securing means therefor, comprising a plate having an as opening extending through the same transversely thereof, and a rib extending from one face of the plate concentric to said opening and spaced apart therefrom, providing a recess about one end of the opening, a screw having a head cooperating with the opposite face of-the plate, and a threaded shankof less diameter than said opening projecting through the same and beyond the first-named face of the plate, and a flat disk frictionally secured to said projecting portion of the shank and slidable lengthwise thereof in one direction, said disk being adapted tooccupy said recess and cooperate with the bottom thereof for preventing 10o accidental detachment of the screw from the plate by a relative movement of the screw in one direction, substantially as and for the purpose described.-

5. A screw retaining device comprising a washerhavingahollow projected, truncated, substantially conoidal boss, and a perforation at the top of the boss for receiving the screw, the major part of the boss being comtoward the plane of the washer, the wall of the boss being tapered toward the perforation and the margin thereof around the perforation condensed sothat it is rigid compared with the major part of the boss, the condensed edge being designed to take into the threads of the screw, substantially as and for the purpose specified.

6. A screw retaining device comprising a washer having a hollow, projected, truncated, conoidal boss and a perforation at the top of the boss, the perforation being of less diameter than the screw the device is designed to be used with, and the edgeof'the boss around the perforation being com- .1

pressed thinner than the normal thickness of the wall of the boss forming a thin edge to take into the threads of'the screw, substantially as and for the purpose set forth.

7. screw retaining device comprising a washer having a hollow, projecting truncated, substantially conoidal boss, and a perforation at the top of the boss of less diameter than the screw the device is designed to be used with, the margin of the boss around the perforation being condensed forming a thin margin, rigid compared with the remaining portion of the boss. and the outer face of the boss being convex and curving into a plane approximately parallel to the body of the washer as said surface nears the perforation, the inner face being conical,

substantially as and for the purpose described.

In testimony whereof, I have hereunto signed my name in the presence of two attesting witnesses, at Syracuse, in the county of Onondaga, and State of New York, this 2nd day of March, 1914.

EDWIN E. GREAVES.

Witnesses:

WM. CORNELL BLANDING, C. C. SCIIOENECK. 

